Search results for "matemàtica"
showing 10 items of 147 documents
Preferencias entre unidades eficientes : una aplicación de supereficiencia fuzzy basada en niveles de exigencias
2014
En el contexto económico actual, lograr el máximo de eficiencia es una cuestión clave para las empresas. En ocasiones, los métodos clásicos de análisis de la eficiencia, como el Data Envelopment Analysis (DEA), no ofrecen al empresario información suficiente al clasificar las unidades de decisíon en dos grupos, las eficientes y las ineficientes. Los gestores demandan más información sobre la eficiencia de su empresa, de modo que la puedan comparar con la del resto de firmas y conocer su posición relativa dentro del grupo de empresas eficientes o ineficientes. En este trabajo se propone un enfoque, basado en la lógica fuzzy, que completa los modelos DEA clásicos y permite, a partir de los mo…
Algorithms for solving the inverse problem associated with KAK =A^(s+1)
2017
In previous papers, the authors introduced and characterized a class of matrices called {K,s+1}-potent. Also, they established a method to construct these matrices. The purpose of this paper is to solve the associated inverse problem. Several algorithms are developed in order to find all involutory matrices K satisfying K A^(s+1) K = A for a given matrix A∈C^(n×n) and a given natural number s. The cases s=0 and s≥ are separately studied since they produce different situations. In addition, some examples are presented showing the numerical performance of the methods.
Algorithms for {K, s+1}-potent matrix constructions
2013
In this paper, we deal with {K, s + 1}-potent matrices. These matrices generalize all the following classes of matrices: k-potent matrices, periodic matrices, idempotent matrices, involutory matrices, centrosymmetric matrices, mirrorsymmetric matrices, circulant matrices, among others. Several applications of these classes of matrices can be found in the literature. We develop algorithms in order to compute {K, s + 1}-potent matrices and {K, s + 1}-potent linear combinations of {K, s + 1}-potent matrices. In addition, some examples are presented in order to show the numerical performance of the method. (C) 2012 Elsevier B.V. All rights reserved.
Ambigüedad y polisemia del signo radical:un problema matemático y didáctico
2014
La ambigüedad de la raíz cuadrada y la polisemia del signo radical plantean un problema con raíces históricas. Como problema matemático ha sido resuelto, pero no como problema didáctico, ya que presenta sutilezas conceptuales y operatorias cuya omisión en la enseñanza es a menudo causa de malentendidos y conflictos fuertemente arraigados. En este artículo se aborda este problema en su dimensión matemática desde una perspectiva histórico epistemológica. Esta perspectiva permite sustentar una reflexión didáctica.
Introducing migratory flows in life table construction
2012
The purpose of life tables is to describe the mortality behav iour of particular groups. The construction of general life tables is based on death statis tics and census figures of resident populations under the hypothesis of closed demographic sys tem. Among other assumptions, this hypothesis implicitly assumes that entries (immigrants) a nd exits (emigrants) of the population are usually not significant (being almost of the same magnitu de for each age compensating each other). This paper theoretically extends the classical sol ution to open demographic systems and studies the impact of this hypothesis in constructing a life table. In particular, using the data of residential variations m…
Bounds on the number of maximal subgroups of finite groups
2023
In this paper we obtain significant bounds for the number of maximal subgroups of a given index of a finite group. These results allow us to give new bounds for the number of random generators needed to generate a finite $d$-generated group with high probability.
Curves with constant curvature ratios
2004
Curves in ${\mathbb R}^n$ for which the ratios between two consecutive curvatures are constant are characterized by the fact that their tangent indicatrix is a geodesic in a flat torus. For $n= 3,4$, spherical curves of this kind are also studied and compared with intrinsic helices in the sphere.
On finite T-groups
2003
[EN] Characterisations of finite groups in which normality is a transitive relation are presented in the paper. We also characterise the finite groups in which every subgroup is either permutable or coincides with its permutiser as the groups in which every subgroup is permutable.
Real elements and p-nilpotence of finite groups
2016
Our first main result proves that every element of order 4 of a Sylow 2-subgroup S of a minimal non-2-nilpotent group G, is a real element of S. This allows to give a character-free proof of a theorem due to Isaacs and Navarro (see [9, Theorem B]). As an application, the authors show a common extension of the p-nilpotence criteria proved in [3] and [9]. The first and the second authors have been supported by the grant MTM2014-54707-C3-1-P from the Ministerio de Economía y Competitividad, Spain, and FEDER, European Union. The first author has been also supported by a project from the National Natural Science Foundation of China (NSFC, No. 11271085) and a project of Natural Science Foundation…
Application of a self-learning methodology for the enhancement of the oral communication student outcome in International Business studies
2019
[EN] Effective oral communication is one of the most demanded student outcomes in the labour market, especially for degree students on International Business. Although this outcome is usually evaluated in several subjects along the curriculum, it is barely worked neither inside nor outside the classroom, mainly due to lack of time and to unavailability of proper learning methodologies. The PIMECOE project, an innovation and educational improvement project on this matter, has developed a self-learning methodology on the Effective Oral Communication student outcome, in which auto-diagnosis tests, selflearning tools and peer assessments are conveniently combined to enhance the proficiency leve…